JPS61159094A - Finned heat exchanger - Google Patents

Abstract

PURPOSE:To permit to uniform the layer of frost between fins, elongate a time until a space between fins is blockaded by frost and reduce the number of defrosting operation by a method wherein respective fins of the groups of fins, arranged in parallel with a given space and air flows therebetween, are corrugated and the pitch of corrugation is set so as to be shortened stepwisely toward the outflow direction of the airflow. CONSTITUTION:The pitch Pf1 of corrugation of the corrugated fin 4 at the inflow part of airflow is long, therefore, disturbance of airflow is not generated easily and the difference between absolute temperature of ambient air, related to the amount of frosting, and saturated humid air corresponding to the temperature of heat exchanging heat transfer surface becomes small. As a result, the thickness of layer 3 of frost at the air inflow part becomes thin. The gradually cooled and dehumidified air generates the disturbance gradually since the pitch Pf is shortened step-wisely toward the outflow direction of air, accordingly, the layer 3 of frost is formed as the result of heat exchange between the cooled and dehumidified air. According to this method, the thickness of layer 3 of frost on the surface of the corrugated fin 4 becomes uniform, a space between fins will never be blockaded even the fins are frosted, the width of ventilating path may be secured widely and the number of defrosting operation may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a heat pump type electric conditioner using electricity as a heat source.
This relates to a 1'4 finned heat exchanger.

BACKGROUND OF THE INVENTION Conventionally, heat exchangers used in electric conditioners, etc., have been described in Refrigerating Techniques Vol. 57, No. 655, "Heat Transfer of Fin Coil Heat Exchangers", p. A finned heat exchanger having a configuration as shown in FIGS. a-b is known.

That is, a finned heat exchanger is constructed by arranging a large number of fins 1 in parallel at predetermined intervals to form a fin group, and by intersecting the heat transfer tubes 2 perpendicularly to the fin group in multiple stages.

Furthermore, each of the fins 1 is processed into a wave shape at a constant pitch Pf in order to improve the heat transfer effect between the fins 1 and a gaseous heat exchange fluid such as electricity.

To explain the operation when such a finned heat exchanger is used during heating operation of a heat pump type air conditioner that uses air as a heat source, the outdoor finned heat exchanger functions as an evaporator, and the ambient air temperature decreases. As a result, the evaporation temperature becomes 0° C. or lower, and water vapor in the electricity adheres to the fin surface as frost 3 to form a frost layer. When the space between the fins 1 is blocked by the frost 3, air cannot flow between the fins 1, the heat exchange capacity decreases, and the heating capacity decreases, so the frost 3 adhering to the surface of the fins 1 is melted. Defrosting operation is in progress.

Problems to be Solved by the Invention However, when the finned heat exchanger with the above configuration is used as an outdoor heat exchanger such as a heat pump type air conditioner, as shown in the second part, Since the turbulence is generated from the air inflow part of the fins 1, more frost layer a is formed in the air inflow part of the fins 1, and the space between the fins 1 is closed in a short time. Therefore, the amount of passing air decreases, and the amount of heat exchange decreases significantly in a short period of time.

Therefore, the heating operation must be interrupted and defrosting operations must be performed frequently, which impairs the comfort during heating and also has poor energy efficiency.

The present invention eliminates the above-mentioned conventional drawbacks, suppresses the space obstruction of frost between the fins during frost formation, extends the time until the space between the fins becomes blocked by frost, and improves comfort during heating. The present invention provides an excellent outdoor heat exchanger that improves energy efficiency.

Means for Solving the Problems The heat exchanger with fins of the present invention is arranged in parallel at regular intervals, and the surface of each fin of a group of fins through which air flows flows is formed into a wave shape, and the wave shape is The pitch Pf is set to become gradually shorter as it goes toward the outflow direction of the airflow.

Effect: With the above-described configuration, the airflow is gradually disturbed in the outflow direction of the airflow, and heat exchange is promoted. Therefore, the frost layer between the fins can be made uniform, and the space between the fins can be prevented from being blocked by frost. It is possible to extend the time required for heating, reduce the number of defrosting operations, improve comfort during heating, and improve energy efficiency.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1a and 1b.

FIG. 1a is a plan view of the fin shape of the finned heat exchanger of the present invention, in which the fins are formed by corrugated fins 4 formed in a wave shape on the fin surface and a large number of heat transfer tubes 2 through which a refrigerant flows. A heat exchanger is configured. Note that the arrow indicates the direction of electricity inflow.

Fig. 1 is a detailed view of the air inflow end of the corrugated fin 4 along line A-A' in Fig. 1a. Pf□〉Pff)Pf3)Pf,)Pf
It is set so that it becomes s.

By adopting the above configuration, the corrugated fin 4
In the airflow inflow section, the waveform pitch Pf1 of the waveform fins 4 is long, so airflow is less likely to be disturbed, and the absolute humidity difference between the surrounding air, which is related to the amount of frost formation, and the saturated humid air, which corresponds to the heat exchange heat transfer surface temperature, is becomes smaller.

As a result, the thickness of the frost layer 3 at the air inflow portion of the corrugated fins 4 becomes thinner. The gradually cooled and dehumidified air gradually becomes turbulent because the waveform pitch Pf of the corrugated fins 4 is gradually shortened in the air outflow direction. Heat is exchanged and a frost layer 3 is formed.

Therefore, the frost 3 on the four surfaces of the corrugated fins forms a frost layer with a uniform thickness, and even if the same amount of frost layer is formed as before, the space between the fins will not be blocked, and a wide ventilation path can be secured. can. Therefore, there is little increase in ventilation resistance, a slight decrease in the amount of air passing through, and a small decrease in the amount of heat exchange.The number of defrosting operations is reduced, improving comfort during heating, and greatly increasing energy efficiency. can be improved.

Effects of the Invention As is clear from the above explanation, the finned heat exchanger of the present invention includes a fin group consisting of a large number of fins arranged in parallel at regular intervals and through which airflow flows, and a fin group consisting of a large number of fins arranged in parallel at regular intervals. consisting of a group of heat transfer tubes inserted at right angles and through which fluid flows, and forming a wave shape on the surface of each fin,
The pitch Pf of the waveform is set to be gradually shorter in the outflow direction of the airflow, so that air turbulence does not occur easily at the air inflow part of the waveform fin, and a frost layer with a uniform thickness is formed over the entire surface of the waveform fin. However, even if the same amount of frost layer is formed as in the conventional case, the space between the fins will not be blocked, and a wide ventilation path can be ensured.

Therefore, there is little increase in ventilation resistance (there is only a slight decrease in the amount of passing air, and the decrease in the amount of heat exchange is also reduced, reducing the number of defrosting operations, improving comfort during heating, and improving energy efficiency. It is possible to greatly improve the
This has great practical effects.

[Brief explanation of drawings]

FIG. 1a is a plan view of the fin shape of a finned heat exchanger showing an embodiment of the present invention; FIG. FIG. 2a is a plan view of the fin shape of a conventional finned heat exchanger, and FIG. 2... Heat exchanger tube, 3... Frost, 4...
-Finn, Pf. ~Pf5... Waveform pitch. Name of agent: Patent attorney Toshio Nakao and 1 other person2.
・ Iyochimi Inner Ship Figure 1 311

Claims (1)

[Claims] A finned heat exchanger consists of a fin group consisting of a large number of fins arranged in parallel at regular intervals, through which air flows, and a group of heat transfer tubes inserted at right angles to the fin group, through which fluid flows. The heat exchanger with fins further has a wavy shape formed on the surface of each of the fins, and the pitch Pf of the wavy shape is shortened step by step toward the outflow direction of the airflow.